Ovulation & Pregnancy Calculator

Fertile window, ovulation day and due date from cycle data.

First day of last period

Cycle length (days)

Ovulation day

Tue, October 20

Fertile windowThu, October 15 → Wed, October 21

Next periodTue, November 3

175 available

Annuity and differentiated monthly installments, interest breakdown, and amortization schedule.

Calculate PITI (Principal, Interest, Taxes, Insurance), PMI, and accelerated payoff savings.

Visualize compound growth with recurring deposits, annual rate, and investment horizons.

Add or extract Value Added Tax (VAT) with international country presets.

Analyze profitability and percentage return on business capital and investments.

Gross to net salary with income tax, social contributions and deductions, monthly and annual.

About this calculator

Fertility calendar from last period and cycle length: ovulation day, fertile window, next period — plus due date (Naegele +280 days).

When is ovulation?

Roughly cycle length minus 14 days after period start; the fertile window spans 5 days before to 1 day after.

How is the due date computed?

First day of last period plus 280 days (40 weeks).

How accurate is it?

Estimates for regular cycles; irregular cycles need a doctor’s dating.